1. Field of the Invention
The present invention is related to a system and method for processing an image, more specifically to a DMA controlled image processing system.
2. Background Art
The image processing system typically interfaces to the display controller through a “frame buffer” of special two-port memory, which can be written to randomly by the graphics processing system, but also provides the synchronous data output needed by the video output driver. (Digital-to-analog conversion is also provided after the frame buffer.) Such a frame buffer is usually implemented using VRAM memory chips (or sometimes with DRAM and special DRAM controllers). This interface relieves the graphics-processing system of most of the burden of synchronization for video output. Nevertheless, the amounts of data which must be moved around are very sizable, and the computational and data-transfer burden of placing the correct data into the frame buffer can still be very large. Even if the computational operations required are quite simple, they must be performed repeatedly on a large number of data points. If blending is desired, additional bits (e.g. another 8 bits per pixel) will be required to store an “alpha” or transparency value for each pixel.
Some image processor requires an image display engine to render a variety of images, each having pixel data in a variety of formats. A number of alternative data formats may be utilized, such as indexed, 16 bit, 24 bit, 32 bit, RGB, YCbCr, 4:2:2, and so forth. When two images in different formats is alpha blended, scaling the original images to a desired output resolution may be required. These scaled images are stored in external buffer memory. These converted scaled images may be then color space converted to the output color format. If rotation is required of either image, that intermediate images also needs to be created and stored before the alpha blending process. Thus, alpha blending of two images of different resolution, different orientation and color space requires external storage buffer. The memory buffers can be configured as frame buffers or line buffers.
However, in the conventional image display engine for alpha blending, alpha blend source images must be same size as destination output and source images must be same color space. Further, the conventional image display engine for alpha blending does not support YUV42x Planar format seamlessly. Moreover, temporary frame buffer to hold intermediate data needs more running time and power consumption.
Accordingly, a need exists for an image processing system and method for processing multiple image data which avoids these and other problems of known systems and methods. The present invention solves these problems to provide alpha blending of two images of different resolution, different orientation and color space utilizing shared logic for multiple image streams and without display storage frame buffer and overcoming a number of deficiencies in the prior image processing systems.